This invention relates to amplifiers employing semiconductor devices. More particularly, it is concerned with high frequency, high gain, amplifier circuits employing field effect transistors.
One type of semiconductor device which provides a combination of high power, high frequency, good gain efficiency, and high breakdown voltage is a form of field effect transistor (FET) known as the static induction transistor (SIT). By employing these devices it is possible to design and implement efficient, high gain, high frequency, power amplifiers and oscillators capable of operating with high DC supply voltages. Static induction transistors are a special class of junction field effect transistors in which electrical current flows "vertically" between the source and drain and is controlled by an induced electric potential barrier under the source.
Amplifiers having high power gain and operating at high frequency with high drain efficiency have been constructed employing a single static induction transistor in the common-gate configuration. Static induction transistors operated in a common-source configuration are capable of providing very high gain at high frequencies. However, when they are operated in this configuration, the inherent parasitic drain-to-gate capacitance provides a positive feedback path which may result in instability and/or oscillation.